The invention relates generally to semiconductor devices and integrated circuit fabrication and, in particular, to structures including identification markings and methods for making such structures.
A wafer is a thin slice of semiconductor material, such as a crystalline silicon, used in electronics for the fabrication of integrated circuits. The wafer serves as the substrate for microelectronic devices built in and over the wafer, and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. Chips are fabricated in parallel across the surface area of the wafer in repeating patterns using a set of masks to replicate the device structures of the integrated circuits. The individual chips are separated by dicing and packaged for end use.
A machine-readable backside wafer identification marking is commonly used to identify the wafer during processing. Wafers are commonly thinned after front side processing and before dicing using, for example, a back side grind that can remove the identification marking. In this instance, provisions may be made to maintain an identification marking that is associated with the wafer. In this regard, an approach is to laser scribe a portion of the wafer front side with a unique identification marking. The wafer identification marking is commonly transferred to a front side of the wafer in a “clear cell” marking region using a laser scribe. The laser scribing process alters the surface topography to construct characters or symbols representing the identification marking. However, the surface alteration may also introduce surface roughness and debris as artifacts of the process forming the marking. The surface roughness and debris reduce planarity and may produce defectivity that reduces yield.
Improved structures including identification markings and methods for making such structures are needed.